13% Left Health Care Rolls, U.S. Finds

WASHINGTON — About 13 percent of people who signed up for health insurance coverage in 2015 under the Affordable Care Act have fallen off the rolls, many because they failed to pay their share of premiums, the Obama administration said Tuesday.

The administration announced in March that 11.7 million people had signed up for coverage through federal and state marketplaces. On Tuesday, federal officials disclosed that enrollment stood at 10.2 million as of March 31.

Sylvia Mathews Burwell, the secretary of health and human services, issued the new enrollment report and highlighted data indicating that 6.4 million people were receiving federal subsidies to buy insurance in states where the marketplace, or exchange, was run by the federal government.

Those federal subsidies could be halted if the Supreme Court rules in favor of critics of the Affordable Care Act, who contend that the law authorized subsidies only in states that established their own exchanges. A ruling is expected in the next four weeks.

Nationwide, the administration said, the federal government is paying insurance subsidies in the form of tax credits to 8.7 million people, including 2.3 million in states that run their own exchanges. The average tax credit for those who qualified for financial assistance was $272 a month, the administration said.

The insurance marketplaces got off to a rocky start in October 2013, and President Obama paid a hefty political price as millions of consumers were frustrated trying to buy insurance. But the administration recovered, after making urgent repairs to HealthCare.gov, and by May 2014 the White House was celebrating the fact that eight million people had signed up for insurance in the first open enrollment period.

Federal officials on Tuesday disclosed that enrollment was substantially lower at the end of the year. About 6.3 million consumers were enrolled in health coverage through the marketplaces and had paid their premiums as of Dec. 31, 2014, they said.

But Ms. Burwell said there had been growth in enrollment since then. “The health insurance marketplaces are working,” she said Tuesday. “We’ve seen a historic reduction in the uninsured, and consumers are finding the coverage they need at a price they can afford.”

In November 2014, less than a week before the marketplaces reopened for the 2015 enrollment period, Ms. Burwell offered a surprisingly modest estimate of the number of people who would sign up for insurance. She set a goal of having 9.1 million people on the rolls, with premiums paid, at the end of December 2015. Administration officials said Tuesday that they were on track to meet or surpass that goal.

Administration officials said they were confident that they would prevail in the pending Supreme Court case, King v. Burwell, and Ms. Burwell says she has not made contingency plans to deal with any disruption of subsidy payments. But the officials appeared to be eager to send a message — to the public and the court — about the hardship that could result from a ruling against the administration.

In its report Tuesday, the administration listed 11 states where more than 90 percent of consumers insured through the marketplace were receiving subsidies. Mississippi had the highest share, at 94.5 percent, followed in order by Florida, North Carolina, Wyoming, Louisiana, Arkansas, Georgia, Alabama, Wisconsin, Alaska and South Carolina.

Without subsidies, many people would be unable to afford insurance.

Of the 10.2 million people who were enrolled at the end of March, the administration said, 68 percent had selected midlevel “silver plans,” and 21 percent were in bronze plans.

While many people lost marketplace coverage because they failed to pay their share of premiums, some could have fallen off the rolls for other reasons — if, for example, they obtained insurance through their employers or became eligible for Medicare or Medicaid.

The government also ended coverage for some people because they could not establish their citizenship or immigration status to the satisfaction of federal officials.

On March 31, the government terminated coverage through federal marketplaces for 117,000 consumers who could not document their citizenship or immigration status. For similar reasons, the government ended coverage for 109,000 people in 2014.

In addition, the government reduced, increased or eliminated subsidies for people whose income was different from what they had initially projected. Because of these “income inconsistencies,” the government said, it altered the subsidy level for 223,000 households this year and 97,000 households last year.

A version of this article appears in print on , on Page A14 of the New York edition with the headline: 13% Left Health Care Rolls, U.S. Finds. Order Reprints | Today’s Paper | Subscribe